While Souths coach Anthony Seibold himself admitted their preparations had been thrown into chaos by the lewd video scandal that broke on Friday, the Dragons have no such dramas.

De Belin didn't train with teammates in the club's captain's run in Wollongong, but after completing a light session McGregor is confident he will be fine to go against the Rabbitohs despite the ankle injury.

"Jack's good, he's in a better position than he was this time last week so that's a very pleasing sign," McGregor said.

"He'll warm up with everything focused about him playing."

De Belin's inclusion is a significant sign of his durability, given he has played all but just a couple of games with a pain-killing injection in either his hip or ankle.

It comes as a massive boost for the Saints, given they are already without State of Origin prop Paul Vaughan for the rest of the year with a foot injury and England international Gareth Widdop with a shoulder problem.

Shutting down the Rabbitohs pack led by Sam Burgess and his in-form brothers Tom and George will be key, given they provide much of the momentum required for Origin hooker Damien Cook out of dummy-half.

"That's where the clashes are won. Your halfback is good when your forwards are going well," McGregor sad

"Jack's a very good player and he proved that in the Origin arena this year for the first time in his career.

"He's not a young bloke anymore and he's well into his career. With that takes leadership and with that experience he gets he needs to bring it into his club."

Meanwhile the Dragons won't play centre Euan Aitken on return from a hamstring injury, with McGregor opting to stick with rookie Zac Lomax to mark Souths superstar Greg Inglis.

"(Euan) is coming back from a hamstring problem ... and he hasn't hit 80 per cent speed. He was available for selection but we're not pushing him at the moment," McGregor said

Meanwhile Souths have their own problems, with Adam Reynolds also requiring a pain-killing injection in his right shoulder to take the field and Inglis also taking a rib issue into the game.

STATS THAT MATTER:

* The loser of the qualifying final has won nine of 12 games in the semi finals under the current finals system.

* Favourites Souths have lost four of their past five, while St George Illawarra have won three of the past four.

Stats: Fox Sports Stats

Australian Associated Press